SAMV7: Quick'n'dirty port of the SAMA5D4 Ethernet MAC driver to the SAMV7.  Still some unresovled issues with DCache handling

This commit enables HSMCI functionality in the SAMV71-XULT.  TX DMA is, unfortunately, currently disabled.

SAMA5:  Fix a bug in SAMA5 HSMCI.  The bitfield mask and shift values were reversed resulting in a trashed value for the number of blocks in the BLOCKR register.  This was sufficient to prevent DMA writes from working.

Fix some bad logic when file system debug is turned on:  Arguments to syslog were missing so that garbage was being printed.

Fix a bug in the FAT unbind() logic.  There were problems with the way certain internal list handling was implemented.  The end result is that newly opened or cloned file structures were never being added to the list of open files.  So when the unmount() happens, it always looked like there were not open files and a crash could ensue.

Pass the umount2() flags to every unbind() implementation.  That is where the the decision to umount or not will be made.

and this one https://www.sdcard.org/downloads/pls/simplified_specs/part1_410.pdf) shows that ACMD23
must be preceeded with CMD55 command as any other ACMD commands.

Also, after the block reading wait loop must be inserted before writing the next block of data to
the sd card

From Dmitry Nikolaev via Jussi Kivilinna